Partitioning the Components of Soil Respiration in a Trenching Experiment at Harvard Forest 2011

Total soil respiration (Rt) is a combination of autotrophic (Ra) and heterotrophic respiration (Rh). We used a trenching method to sever the rooting system surrounding a plot to remove the Ra component within the plot. We used a custom-made automated chamber system to measure soil respiration within the trenched plot and the control in an oak dominated forest with the footprint of the LPH tower. This method has some potential limitations. Reduced water uptake in trenched plots could change soil water content, which is one of the environmental controllers of Rt in many ecosystems. Eliminating root inputs could reduce heterotrophic decomposition of SOM via lack of priming.

总土壤呼吸（Total soil respiration, Rt）为自养呼吸（autotrophic respiration, Ra）与异养呼吸（heterotrophic respiration, Rh）之和。本研究采用壕沟法（trenching method）切断样地周边的根系，以移除样地内的自养呼吸组分。在LPH塔通量贡献区（footprint）范围内的栎树优势林分中，本研究利用定制化自动气室系统，分别测定壕沟处理样地与对照样地的土壤呼吸速率。该方法存在一定潜在局限性：壕沟样地内根系吸水减少可能改变土壤含水量，而土壤含水量是多数生态系统中调控总土壤呼吸的环境因子之一；消除根系输入会因缺乏激发效应（priming effect），降低土壤有机质（Soil Organic Matter, SOM）的异养分解速率。